1. Field of the Invention
This invention relates generally to a novel single use skin-marking device adapted for marking skin with marks that are visible under ultraviolet light and to a method of rendering small cracks and caries in teeth and plaque attached to teeth visible under ultraviolet light.
2. Description of the Prior Art
The use of skin marking compositions to delineate boundaries of body area requiring medical therapy or monitoring, e.g., in conjunction with radiation treatment for cancer, to mark zones for dermatological surgery, to identify areas contacted with allergens, to monitor the status of skin infections and other dermatological purposes, and to identify individual, e.g., one who have paid admission to an event, is conventional. Typically, visible compounds, such as bright purple or other brightly colored dyes or inks have been used See, for example U.S. Pat. No. 3,551,554. Although such dyes and inks are adequate for marking the skin of humans for short periods of time, e.g., a day, these visible dyes are easily removed upon washing and therefore require repeated applications for more extensive periods of skin marking as would be needed for medical purposes described above or a multiple day event. Further, the adverse psychological impact on a patient so marked with a visible dye that is visible in street clothes is significant and is impractical in most situations when an individual is to be identified by a skin mark for more than a day. In fact, in some cases, the knowledge that his or her skin would need to be marked with a visible dye that could not be immediately washed off could even result in a patient seeking an alternative therapy not requiring his or her skin being marked with a visible dye.
U.S. Pat. Nos. 4,572,831 and 4,610,806 describe the use of skin-marking compositions that contain a furanone, which reacts with the skin in about 15-30 minutes after the application thereof to form a reaction product that is invisible under ordinary invisible light but which intensely fluoresce under ultraviolet light. This reaction product resists removal by washing from the marked area for the normal lifetime of the epidermis.
As described in these patents and as shown in FIG. 1 thereof, a fluorogenically-effective concentration of a furanone, preferably fluorescamine, dissolved in an appropriate carrier fluid such as ethanol, DMF or DMSO, is introduced into the reservoir of a marking pen which is in liquid communication with a marking tip constructed of felt, porous plastic or a functional equivalent conventionally employed in the marking pen art. By drawing a line or other mark on the skin of an individual with the tip of the pen, the fluorescanine-containing carrier liquid flows through the tip of the pen and onto the skin, thereby forming along lasting mark thereon which is visible under ultraviolet light. The carrier fluid optionally also contains a coloring agent which is readily washed off the skin which renders the mark temporarily also visible under ordinary light.
Although functionally the skin marking device of these patents perform very satisfactorily, as commercial products they have a number of deficiencies. First, the half life at ambient temperature of a solution of a fluorogenically-effective amount of fluorescamine or other furanone in a dermatologically acceptable liquid is relative short, varying from days to weeks depending on the nature of the liquid, which is unacceptable for most commercial uses. Moreover, its stability is, unfortunately, the shortest in the dermatologically most desirable liquids, such as ethanol. Second, because an acceptable solvent for the furanone typically comprises a volatile organic solvent, the solvent tends to evaporate before the solution is used up, which at best alters the concentration of the furanone therein and at worst causes the solution to dry up entirely, thus reducing the number of times the marking device can be used. Third, a multiple use skin marking device which allows the tip thereof to contact the skin or other tissue of a plurality of patients can create the risk of the spread of the HIV virus or another pathological organism from an infected patient to other patients. Fourth, there is a tendency of persons involved in the skin marking procedure out of habit to treat the skin marking device of these patients in the same manner as a conventional writing instrument and as a result the marking device sometimes ends up in a pocket of a health care provider involved in a skin marking procedure and is thus unavailable for use on another patient by someone else in the same department. Therefore, a marking device which has the functional advantages of the skin-marking device of U.S. Pat. Nos. 4,572,831 and 4,610,806 but lacks the commercial deficiencies thereof would be desirable.
A problem that exists in the dental art is the detection of very small cracks and caries in teeth during a dental examination. Another problem in that dental art is that the visualization of plaque on the teeth, e.g. in conjunction with dental hygiene education, usually employs a dye which leaves a highly visible stain on the teeth which persists until the teeth are cleaned. A means of visualizing plaque without leaving such a stain also would be desirable. The skin marking procedure of the '831 and '806 patents did not seem adaptable to such usages because in the case of plaque it was not apparent that there was sufficient proteinaceous material present therein to produce a well defined fluorescing area under ultraviolet light. In the case of cracks and caries, it would seem likely that the fine line in the case of a crack and in the case of caries the circular area which would be too small to be seen by conventional visual examination would also be too small to permit contact by a solution of the furanone with the proteinaceous pulp accessible through the crack or caries and produce a fluorescing reaction product that would be visible under ultraviolet light.